Caption: Flyer for the 1769 transit of Venus. This flyer was printed to make amateur astronomers and the general public aware of the upcoming transit of Venus across the Sun. When Venus passes directly between the Earth and the Sun, it is seen as a small disc that obscures part of the Sun. This phenomenon is rare, as it occurs in pairs that are spaced by eight years and each pair then has over 100 years between them. Only seven transits of Venus have occurred since the invention of the telescope (in the years 1631, 1639, 1761, 1769, 1874, 1882 and 2004). The second transit in the 21st century is on 6th June 2012, after which the next one is not until 2117.